Scanning mirrors are used in a variety of applications, particularly in projecting and receiving beams of light. For example, U.S. Patent Application Publication 2013/0207970, whose disclosure is incorporated herein by reference, describes a scanning depth engine in which a transmitter emits a beam comprising pulses of light, and a scanner scans the beam, within a predefined scan range, over a scene. A receiver receives the light reflected from the scene and generates an output indicative of a time of flight of the pulses to and from points in the scene. A processor is coupled to control the scanner so as to cause the beam to scan over a selected window within the scan range and to process the output of the receiver so as to generate a 3D map of a part of the scene that is within the selected window.
Various means are known in the art for driving a scanning mirror. For example, PCT International Publication WO 2014/016794, whose disclosure is incorporated herein by reference, describes a dual-axis scanning mirror with a magnetic drive. The drive includes a stator assembly, which includes a core containing an air gap and one or more coils including conductive wire wound on the core so as to cause the core to form a magnetic circuit through the air gap in response to an electrical current flowing in the conductive wire. A scanning mirror assembly includes a support structure, a base, which is mounted to rotate about a first axis relative to the support structure, and a mirror, which is mounted to rotate about a second axis relative to the base. At least one rotor includes one or more permanent magnets, which are fixed to the scanning mirror assembly and which are positioned in the air gap so as to move in response to the magnetic circuit. A driver is coupled to generate the electrical current in the one or more coils.